SHANGHAI (Reuters) - The China release of its iPhone 5 on Friday should win Apple Inc some respite from a recent slide in its share of what is likely already the world's biggest smartphone market, but its longer-term hopes may depend on new technology being tested by China's top telecoms carrier.

Cupertino, California-based Apple has been in talks about a tie-up with China Mobile for four years. A deal with China's biggest carrier is seen as crucial to improve Apple's distribution in a market of 290 million users - which is forecast to double this year.

China is Apple's second-largest and fastest-growing market - it brings in around 15 percent of total revenue - but the company's failure to strike a deal with China Mobile means it is missing out on a large number of phone users. As the China pie grows, Apple's sales increase, but without China Mobile, it's losing ground at a faster rate compared to other brands.

"In absolute terms, this (iPhone 5) launch will certainly result in strong sales for Apple in China. However, in relative terms, I don't believe it will move the needle enough in market share," said Shiv Putcha, a Mumbai-based analyst at Ovum, a global technology consultant.

On Friday, just one person was waiting outside the Apple store in Shanghai's financial district when its doors opened at 9 a.m., a contrast to the launch of the iPhone 4 earlier this year when rowdy crowds pelted a Beijing store with eggs.

China Mobile and Apple initially said they were separated only by a technical issue - as the Chinese carrier runs a different 3G network from most of the world - but that has evolved into a broader and more complex issue of revenue-sharing.

"China Mobile and Apple still have to solve many issues, such as the business model, articles of cooperation and revenue division, but I believe we will reach an agreement eventually," China Mobile CEO Li Yue was reported by Chinese media as saying in Guangzhou last week.

Apple China declined to comment. China Mobile said it had no update to the Apple discussions.

STRONG PRE-ORDERS

Apple's ranking in China's smartphone market slipped to sixth in July-September, according to research firm IDC, but investors, primed to look to China product launches for an uptick in Apple's quarterly sales, have good headline numbers to digest - more than 300,000 iPhones pre-ordered on one carrier alone. But it's the lack of a deal with the No.1 carrier that prevents those numbers being stronger.

The iPhone is currently sold through Apple's seven stores, resellers and through China Unicom and China Telecom - which together have fewer than half the mobile subscribers of bigger rival China Mobile.

"Apple's market share declined because of the transition between the iPhone 4S and 5. Their market share will recover (with the iPhone 5), but if you don't have China Mobile, the significant market share gains will be very difficult," said Huang Leping, an analyst at Nomura in Hong Kong.

TD-LTE: STILL DISTANT

Cutting a deal with a Chinese state-owned carrier may be less optimal than the deals Apple is used to in other markets, and analysts note that China Mobile wouldn't necessarily open the flood gates for Apple.

Ovum's Putcha believes Apple and China Mobile will eventually strike a deal - though this would be for an iPhone running on China Mobile's next-generation network rather than its current 3G network.

Of China Mobile's 704 million subscribers, only 79 million are on its 3G network, and Apple has been reluctant to sign up to China Mobile's under-utilized, homegrown TD-SCDMA technology. "Apple likely doesn't see the return-on-investment in extending themselves for TD-SCDMA," Putcha said.

China Mobile is currently trialing its next-generation network, TD-LTE, which could be of more interest to Apple, but full-scale commercial use - and an iPhone tie-up - could still be years away.

ANDROID THREAT

Meanwhile, rivals are circling, eating away at Apple's smartphone market share. Samsung Electronics, Lenovo Group and little-known Chinese brand Coolpad held the top three slots in the third quarter, according to IDC.

All three have relationships with China Mobile and offer smartphone models at different price points. Apple competes exclusively at the high-end, and even there, rivals are rolling out models with China Mobile. Last week, Nokia said it planned to release its latest Lumia smartphone with China's top carrier, which is also expected to launch Research in Motion's new Blackberry 10, analysts predict.

"The threat will still come more from the Android camp where they have many vendors already working with China Mobile and offering high-end phones," said TZ Wong, a Singapore-based IDC analyst.

While these smartphones don't generate the buzz of a new iPhone, Chinese buyers are not known for their brand loyalty, and this could siphon away users considering an Apple upgrade.

"I've used a Blackberry, Android and iOS and, personally, I want to try the Windows 8," said Andy Huang, a 37-year-old fund manager, who owns most iPad models, an iPhone 4 and a 4S. "I think the Windows 8 is very innovative."

With a China Mobile deal looking some way off, Apple could always boost market share by offering cheaper models - the basic iPhone 5 will cost 5,288 yuan ($850) without a contract - though this appears an unlikely route for a high-end brand.

"If they want to expand market share, probably the only way to do it here dramatically would be to put out a lower cost phone," said Michael Clendenin, managing director at RedTech Advisors. "It's really uncertain if they'd decide to go that route ... Apple's a mystery in that regard."